You know what, even the 2d Sonics weren't all that good.
They were built around being cheap. A random spike falls on you, a platform falls out from under you, an obstacle you could never predict is in front of a spring you didn't know was there. Sonic games were all about dying a lot, and learning where the pitfalls were.
Mario platformers by contrast, never really felt cheap. Those were more about learning how to deal with enemy types, and exploring levels from top to bottom, but if you died you always knew it was your fault, and avoidable.